It is well known to produce metal molds such as steel, composite or nickel shells that are built into molds for lay up and curing of composite materials. For example, reference is made to U.S. Pat. No. 3,666,600 to Yoshino issued May 30, 1972; U.S. Pat. No. 4,562,033 to Johnson et al issued Dec. 31, 1985 and U.S. Pat. No. 5,106,568 to Honka issued Apr. 21, 1992.
US Patent Publication 2009/0214874 Voss et al. published Aug. 27, 2009, the disclosure of which is incorporated herein by reference, teaches the manufacture of molded fiber composite panels for an automobile such as panels useful for fascia engine hoods, front quarter panels, doors, rear quarter panels, rear trunk decks, pillars, roofs rocker panels, interior trims, exterior trims, spoilers, door handles, mirror covers, air diffusers, and fascia extensions. Voss et al teaches that a such panels may be made by a first method involving autoclave molding of a hand lay up of fiber-epoxy prepreg using a single-sided metal or composite tool. The panels may be produced by first cutting the prepregs to the shape of the part using an automated pattern-cutting machine. A predetermined number of plies of the patterned prepregs may be manually laid up in the tool cavity, and covered and sealed with a silicone rubber vacuum bag to evacuate the air trapped between the plies. The assembled prepreg plies may be subsequently consolidated and cured in an autoclave at an elevated temperature under pressure for a given period of time. The autoclave then may be cooled down and depressurized for the cured prepregs to be removed from the single-sided tool. The cured prepregs are trimmed, inspected, and finished to produce the final composite panels. Another second method of making composite panels involves resin transfer molding of fiber performs in a matched-metal or composite tool. The fiber preforms can be made by heating and pressuring patterned lay ups prepared from continuous random fiber mats, unidirectional fiber tapes, or woven fiber fabrics. The fiber preforms can also be made by lay up molding by directly spraying chopped fibers onto a preform mold or by depositing chopped fibers onto a perform mold using a water or liquid slurry process. The shaped fiber preforms may be placed in the matched-metal or composite tool and the epoxy resins are subsequently injected into the closed tool cavity. The tool may be kept at an elevated temperature under pressure for a given period of time to impregnate the fibers with epoxy resins and to form the cured composite panels.
As disclosed by Voss et al, a typical automotive fiber-epoxy prepreg material which may be utilized according to one exemplary embodiment is the P831-190 carbon fiber-epoxy prepreg produced by Toray Composites. The prepreg is made with Toray's T-600 24 k unidirectional carbon fiber (60 wt %) and G83C epoxy resin (40 wt %). Similar commercial prepreg materials, in both unidirectional tape and woven fabric forms, are available from prepreg suppliers such as Advanced Composites Group (ACG) and Hankuk Carbon Company using carbon fibers produced by Toray, TohoTenax, Zoltek, etc. The prepregs can be cured at 150° C. (peak temperature) under 0.7 MPa pressure for 10 minutes. A full cycle of the autoclave molding takes approximately 90 minutes to complete. The molding cycle consists of loading, pressurizing, ramping up to 150° C., cooling down, depressurizing, unloading and demoulding.
Where a resultant product is desired to have trapped portions such as under cuts, it is known to provide the mold with removable tool inserts that are manually placed on the mold in dedicated positions and locked into position. Composite material is laid up under the trapped geometry formed by the insert. After material curing, the insert is manually removed from the mold to permit removal of the cured rigid resultant product with the molded trapped geometry. Securely locking the inserts into position prevents movement and minimizes witness lines.
Known loose inserts for lay up molds suffer disadvantages that are handled manually and must always be handled carefully to prevent misalignment. The applicants have appreciated that the dropping of loose inserts has the severe disadvantage of resulting in damaged inserts or more significant damage to the mold face. Manual handling has the disadvantages of requiring dexterity, skill and time.
After molding, the resin of the cured product freezes the insert in place as by adhering to surfaces of the insert, and significant force is normally needed to disengage the insert from the product. Such adherence may be overcome by manual prying as with use of a prying bar, however, such lifting of the insert having the disadvantage of requiring careful handling to avoid damaging the insert or having the insert when released strike the mold.
Manual handling of the inserts has been appreciated by the applicants as having the disadvantage of requiring a significant cycle time for the molding process, and a need for significant skill level for the operators, which need increases as production volumes and applications increase.